Effect of pore geometry and interfacial tension on water-oil displacement efficiency in oil-wet microfluidic porous media analogs

Abstract

Using oil-wet polydimethylsiloxane (PDMS) microfluidic porous media analogs, we studied the effect of pore geometry and interfacial tension on water-oil displacement efficiency driven by a constant pressure gradient. This situation is relevant to the drainage of oil from a bypassed oil-wet zone during water flooding in a heterogeneous formation. The porosity and permeability of analogs are 0.19 and 0.133–0.268 × 10−12 m2, respectively; each analog is 30 mm in length and 3 mm in width, with the longer dimension aligned with the flow direction. The pore geometries include three random networks based on Voronoi diagrams and eight periodic networks of triangles, squares, diamonds, and hexagons. We found that among random networks both pore width distribution and vugs (large cavities) decreased the displacement efficiency, among the periodic networks the displacement efficiency decreased with increasing coordination number, and the random network with uniform microfluidic channel width was similar to the hexagon network in the displacement efficiency. When vugs were present, displacement was controlled by the sequence of vug-filling and the structure of inter-vug texture was less relevant. Surfactant (0.5 wt. % ethoxylated alcohol) increased the displacement efficiency in all geometries by increasing the capillary number and suppressing the capillary instability.

Oil/water displacement in microfluidic packed beds under weakly water-wetting conditions: competition between precursor film flow and piston-like displacement

“…Microfluidic studies of two-phase, oil/water displacement processes typically involve the addition of dye to the aqueous phase to facilitate visualization (e.g., Geistlinger et al 2016;Frette et al 1997;Chevalier et al 2015;Xu et al 2017;Yun et al 2017;Kumar Gunda et al 2011;Xu et al 2014;Cottin et al 2010;Yeganeh et al 2016;Levaché and Bartolo 2014;Datta et al 2014) unless opaque crude oil is used (e.g., Song and Kovscek 2015;Zhu and Papadopoulos 2012;Bowden et al 2016). However, many enhanced oil recovery and NAPL-remediation approaches involve the addition of chemical additives such as surfactants and polymers to the water that is injected into the system to displace the oil.…”

Viscosity Measurements of Different Fluids Used for Mobility Control in Mature Reservoirs

“…Eventually, the fingers break through and the water cut begins to climb. It becomes far more difficult for the displacing solution to force much of the remaining oil out, as the pressure required to overcome capillary forces is larger than the pressure required to flow through the breakthrough zones [2,8]. As a result, capillary bypassing takes place, causing oil to be surrounded by displacing fluid and trapped [9,10].…”

“…This can be done using mechanical methods or chemical methods, generally targeting particular permeability zones or viscosity issues. The goal is to reduce reservoir heterogeneity and increase recovery [2]. Properly adjusting the viscosity of the displacing phase, the interfacial tension, or the interfacial viscosity can increase sweep efficiency [3].…”

Swelling and Deswelling Kinetics of AT-O3S Polymer

“…Although it is a very useful technique, there are some drawbacks. Heterogeneity in reservoir permeability causes an increase in the amount of water produced over time [2]. This translates to greater production costs [3].…”

“…Excess water production is often caused by differences in the permeability of a reservoir, which can affect fluid movement significantly [2,7,8]. Since injected water flows through the high permeability zones first, they are cleared of oil first, and water production begins to increase dramatically [9].…”